1. Field of the Invention
The present invention relates to a two-stroke engine.
2. Description of the Related Art
In a Schnurle type two-stroke engine having no intake valve and no exhaust valve, a two-stroke engine is known in which a fuel injector is arranged on the inner wall of the cylinder and fuel is injected from the fuel injector in such a manner that it moves forward along the stream of the scavenging flow of fresh air, which is forced into the shape of a loop (see Japanese Examined Patent Publication No. 45-157621. In this two-stroke engine, fuel injected from the fuel injector is made to move together with the scavenging flow and is carried thereby up to the spark plug so that the air-fuel mixture is easily ignited by the spark plug.
Where the injected fuel is made to move together with the scavenging flow, however, the injected fuel collects in the vicinity of the inner walls of the cylinder and the cylinder head, due to centrifugal force, and as a result, since a homogeneous air-fuel mixture is not formed in the combustion chamber, a problem occurs in that a good combustion cannot be obtained, particularly when the engine is operating under a heavy load. Further, where the injected fuel is made to move together with the scavenging flow, a part of the injected fuel adheres to the inner walls of the cylinder and the cylinder head, and thus another problem occurs in that a large amount of unburned HC is produced and discharged.